Optical communications systems using optical fibers to convey information between a light source and a light detector are presently of significant and growing commercial interest.
An optical communication technique uses optical amplifiers to span long distances. The optical amplifiers used in such technique can have a segment of a rare earth doped length of optical fiber which is pumped by a light source. The light source used in such systems is commonly a semiconductor laser. The doped segment of optical fiber amplifies the incoming optical signal and emits an amplified optical signal. An exemplary dopant is erbium and erbium doped fiber amplifiers are often referred to by the acronym EDFA.
Semiconductor laser diodes are susceptible to high current and high voltage electrical transients, such as electrical static discharge (ESD) or electrical over stress (EOS). The large continuous wave (CW) current needed to drive a semiconductor pump laser to achieve a high optical power makes semiconductor pump lasers even more vulnerable to electrical transients under normal operation. Specifically, nine-hundred eighty (980) nm pump lasers can be damaged due to EOS in the laboratory and in the field.
A commercially available transient suppressor used to provide a short turn-on time (e.g., &lt;1 ns) is a Zener diode. Zener diodes only protect against drive current transients in a single current direction, however.